Previously, we only validated/converted on the way to the server,
but not from the server.
Validating both ways catches issues earlier, and allows us to
perform automatic conversions, for example only converting
buffers to base64 when sending over wire.
This changes PlaywrigtServer to serve connections like `ws://localhost:3333/?browser=chromium`:
- launches the browser;
- talks `browserType.connect`-style protocol over websocket;
- compatible with `connectOptions` fixture.
```js
await playwright.chromium.connect({ wsEndpoint: 'ws://localhost:3333/?browser=chrome' });
```
1. Fixtures defined in test.extend() can now have `{ option: true }` configuration that makes them overridable in the config. Options support all other properties of fixtures - value/function, scope, auto.
```
const test = base.extend<MyOptions>({
foo: ['default', { option: true }],
});
```
2. test.declare() and project.define are removed.
3. project.use applies overrides to default option values and nothing else. Any test.extend() and test.use() calls take priority over config options.
Required user changes: if someone used to define fixture options with test.extend(), overriding them in config will stop working. The solution is to add `{ option: true }`.
```
// Old code
export const test = base.extend<{ myOption: number, myFixture: number }>({
myOption: 123,
myFixture: ({ myOption }, use) => use(2 * myOption),
});
// New code
export const test = base.extend<{ myOption: number, myFixture: number }>({
myOption: [123, { option: true }],
myFixture: ({ myOption }, use) => use(2 * myOption),
});
```
